Video footage of unarmed, peaceful student protesters at UC-Davis being calmly, deliberately pepper-sprayed, repeatedly, by a police officer (later identified as UC=Davis Police Lt. John Pike) as hundreds of other students chant “Shame on you! Shame on you!” is all over the Internet. It looks, Xeni Jardin writes, “as if he’s dousing a row of bugs with insecticide.”

Then fast-forward to the end of the clip (around 6:15), when the students announce to the officers that they are offering them “a moment of peace,” that is, the option of leaving without further escalating a truly horrible situation. They cry (in one of the most moving instances of the human mic I’ve ever seen) “You can go! You can go!”

It’s transcendently brilliant, this tactic–the students offer an alternative in a high-pressure situation, a situation that no one wants, but which seems inevitable in the heat of the moment. It’s an act of mercy which, like all acts of mercy, is entirely undeserved. Watch the other officers’ surprise at this turn in the students’ rhetoric, after they had (rightfully) been chanting “Shame on you!” Watch the officers seriously consider (and eventually accept) the students’ offer.

As the officer in the left foreground teeters back and forth, nervous, braced, thinking, watch the power-drunk cop on the right (who I think is the one who pepper-sprayed the crowd earlier) brandish not one but TWO bottles of pepper-spray, shaking them, not just in preparation, but in anticipation. He’s seconds away from spraying the students again. His mask is up, you can see his face, but it’s a nonexperience: it’s blank, immobile. It would be inaccurate to say that he’s immune to the students’ appeal; he’s not even bothering to listen. All he hears are sounds. No signals, all noise. Luckily, it’s made clear to him in time that this colleagues are in retreat, and he does not spray them again.

Strange to seek a lesson on the police side of this appalling moment in our country’s history, but there is one, I think, when you look at the faces behind the riot masks. Look at the expressions. So many are human, attentive, defensive, even regretful, but his is impassive, glutted and red with a chemical thrill. If he is indeed the same officer who sprayed the students earlier, he’s already made the decision to spray once. It’s much easier to jump that moral hurdle a second time.

It’s a truism to say that a chain is only as strong as its weakest link, but here’s the thing: until the students call the rest of the officers to their senses in a truly exceptional act of grace, that doughy nugget of unthinking cruelty is winning.